1. Field of the Invention
This invention relates to a method of detecting one or more liquid hydrocarbons in a mixture of liquid hydrocarbons. More particularly, it relates to the use of a fluorescent compound invisible to the naked eye.
2. Discussion of the Prior Art
Heretofore gasolines and other fuels have had added to them certain dyes to identify and to segregate them. U.S. Pat. No. 3,164,449, for example, discloses the use of anthraquinone dyes for use in gasoline, as do U.S. Pat. No. 3,435,054 and U.S. Pat. No. 3,597,257.
However, detection has been difficult, if not impossible, in those instances in which some individuals have mixed gasolines of the same type, but of different grades. Thus, mixing of premium leaded gasolines with regular leaded gasolines is not unknown. With the advent of the unleaded gasolines, both "regular" and "premium", there are known instances in which these have been mixed.
Applicants know of no prior art teaching the use of alkylated isodibenzanthrone to detect the presence of, for example, a regular unleaded mixed with a premium unleaded. There are two known references from the Oil and Gas Journal that disclose the use of "131 Super Concentrate," which is the designation of the fluorescent material utilized herein to detect batch changes in liquid-petroleum product pipelines. These are "Fluorometer, Dye Spot Interfaces" by F. F. Shamp, Oil and Gas Journal For September, 1965, and "Interface-detection systems tests," by G. M. Jeffanes et al., Oil and Gas Journal, May 14, 1973.